What do the Christians say about this?

Okay, so let's assume the Yahweh of legend exists and that there is life elsewhere in the universe. Now, granted, it's unlikely that life elsewhere is human or even humanoid. Is Jesus their savior, too? So that on a planet where the intelligent form of life is kinda like a half spider/half newt thing or a puddle of slime, is there a half spider/half newt or slime Jesus for them as well? God might actually love them more, actually. He put us in a forsaken corner of an insignificant galaxy. There are far more interesting places to be than the Milky Way. Why put the species he loves best here?

"Now, granted, it's unlikely that life elsewhere is human or even humanoid."

I'd say this is so vastly improbable as to reasonably rule it out altogether. A lot of this boils down to anthropormorphic thinking - as in a loving god - who "puts" his creations in various parts of the universe only to be bombarded by asteroids and eventually incinerated when stars go supernova.

Science fiction about space aliens and space travel is almost always far more fiction than science. On Star Trek, for example, almost all aliens are anthropoid and speak English (the cosmic language, apparently). Space ships can get all around the entire universe in just days if not hours. There is never any danger from gamma rays or from the fact that space isn't really empty, and there are all kinds of things flying around that at the speeds these ships must be going would doom any space ship. Whenever there's a practical problem like that, some improbable and undefined solution is trotted out, such as a force field or shield of some sort. And then there's the absurdity of wormholes, the problem being that wormholes are associated with black holes, and anything going into a black hole gets destroyed on the way in. If something came out the other end it's highly unlikely it'd resemble what went in in the first place.

Space opera-style science fiction is fun, but it's almost all fairy tales. Good science fiction tends to be about things here on earth, such as runaway diseases, nuclear disasters, etc.

Of some predictable folk, human nature would almost certainly find a way to worship these aliens. If we did find them, or rather, advanced aliens found US, with complete knowledge of the universe, there would be mass chaos. Some would think they are demons and try to kill them. We would see an increase in suicide & xenophobia. There is also the scary yet minute possibility that if we do get visited by a aliens, that THEY bring their own version as to how the universe began, complete with a god they say is real, yet have no proof of...

Actually, while it's unlikely—given the vast distances, radiation dangers, and the danger of running into objects in space at great speed—that we or anyone else are traveling very far, if we did, we might need religion to keep from going insane. For example, imagine you're a kid in a spacecraft discovering that someone a couple centuries ago committed you to living in a confined metal hull propelling dangerously through the vast cold blackness of space instead of having picnics and going to baseball games on The Blue Planet, you'd need some way to deal with the anger.

The late Larry Norman, a singer-songwriter often credited as the "father of Christian rock", in a song called UFO, wrote:

And if there's life on other planetsthen I'm sure that He must knowAnd He's been there once alreadyAnd has died to save their souls

I was a huge fan of Larry Norman in my misspent youth (that is, my younger days in which I went to church and youth group instead of going out carousing). I still have a soft spot for many of his songs even though I now think that he was more-or-less insane.